DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1 – 4, 10, 12, 17 – 18 and 20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Tanaka et al. (JP 2016213473).
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(Claim 1) Tanaka et al. teach a SiC semiconductor device comprising:
a SiC chip that has a main surface (Embodiment 1, 2nd – 8th paragraph); and
an n-type drift region (11) that is formed as a layer extending along the main surface in a surface layer portion of the main surface, includes at least two types of pentavalent elements within the same layer, and has an impurity concentration adjusted by the at least two types of pentavalent elements,
wherein the at least two types of pentavalent elements of the drift region include arsenic and antimony, and
both arsenic and antimony coexist within the same layer (11).
(Claim 2) Tanaka et al. teach wherein the drift region has an impurity concentration that is adjusted such as to increase toward the main surface (Embodiment 1, 8th paragraph, “In the high-concentration layer 21, NA, NB, and the difference between NA and NB do not necessarily have to be uniform, and may vary, for example, in the thickness direction (vertical direction in FIG. 2)”).
(Claim 3) Tanaka et al. teach wherein the drift region has an impurity concentration adjusted by pentavalent elements other than phosphorus (Embodiment 1, 8th paragraph).
(Claim 4) Tanaka et al. teach wherein the drift region includes nitrogen as a pentavalent element (Embodiment 1, 8th paragraph).
(Claim 10) Tanaka et al. teach a SiC semiconductor device comprising:
a SiC chip that has a main surface (paragraphs 2 – 8 under Embodiment 1); and
a p-type drift region that is formed in a surface layer portion of the main surface, includes at least two types of trivalent elements within the same layer, and has an impurity concentration adjusted by the at least two types of trivalent elements other than boron (Embodiment 1, 8th paragraph),
wherein the drift region has an impurity concentration that is adjusted such as to increase toward the main surface (Embodiment 1, 8th paragraph, “In the high-concentration layer 21, NA, NB, and the difference between NA and NB do not necessarily have to be uniform, and may vary, for example, in the thickness direction (vertical direction in FIG. 2)”).
(Claim 12) Tanaka et al. teach wherein the drift region includes the at least two types of trivalent elements among aluminum, gallium, and indium (Embodiment 1, 8th paragraph).
(Claim 17) Tanaka et al. teach wherein the drift region has a thickness belonging to any one range among not less than 1 um and not more than 5 um, not less than 5 um and not more than 10 um, not less than 10 um and not more than 15 um, not less than 15 um and not more than 20 um, and not less than 20 um and not more than 25 um (Embodiment 1, 6th paragraph).
(Claim 18) Tanaka et al. teach wherein the SiC chip is constituted of an SiC monocrystal that is a hexagonal crystal, and the main surface is arranged along a c-plane of the SiC monocrystal and has an off angle of not more than 10° with respect to the c-plane (Embodiment 1, 4th paragraph).
(Claim 20) Tanaka et al. teach wherein the drift region is formed in an SiC epitaxial layer (Embodiment 1, 4th paragraph).
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim 19 is rejected under 35 U.S.C. 103 as being unpatentable over Tanaka et al. (JP 2016213473) in view of Kawada et al. (US 2018/0061960).
(Claim 19) Tanaka et al. lack wherein the off angle has an off direction oriented along an a-axis direction of the SiC monocrystal.
However, Kawada et al. teach wherein the off angle has an off direction oriented along an a-axis direction of the SiC monocrystal (fig. 13A, paragraph 57) for the benefit of improving electron mobility (paragraph 58).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the references for the benefit of improving electron mobility.
Allowable Subject Matter
Claims 5 – 9, 21 and 22 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Claims 13 – 16, 23 – 26 are allowable, because prior does not render obvious:
(Claim 13) an impurity concentration adjusted by the at least two types of trivalent elements other than boron;
wherein the drift region has a basal concentration due to a first impurity that is a trivalent element and an added concentration due to a second impurity that is a trivalent element different from the first impurity.
(Claim 23) wherein the drift region has a basal concentration due to a first impurity that is a pentavalent element and an added concentration due to a second impurity that is a pentavalent element other than the first impurity,
the at least two types of pentavalent elements of the drift region include arsenic and antimony, and both arsenic and antimony coexist within the same layer.
(Claim 25) wherein the drift region has a basal concentration due to a first impurity that is a pentavalent element and an added concentration due to a second impurity that is a pentavalent element other than the first impurity, and the added concentration has a concentration distribution that increases toward the main surface.
(Claim 26) has an impurity concentration adjusted by a trivalent element other than boron;
wherein the drift region has a basal concentration due to a first impurity that is a trivalent element and an added concentration due to a second impurity that is a trivalent element being the same as or different from the first impurity, and
the added concentration has a concentration distribution that increases toward the main surface.
Conclusion
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/IGWE U ANYA/Primary Examiner, Art Unit 2891
June 4, 2026
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